Spontaneous Combustion

[Bob Riefer]

Wow, good info. I use a ceiling mounted reel for connecting to my router and sander all the time, and will need to check into whether it's an issue... I like only having a little bit of cord out when only a little bit is needed, but I also like being a fire-free space.

Also, to the OP, glad things ended up ok in your case. Scary stuff and a great reminder. I too use the "lay out flat on concrete" method as that was how I was taught during woodworking class many years ago.

[Brian Tymchak]

Wait, what about cord reels? I haven't heard that one before, please tell

New info for me too. I don't use a reel either but good to have the awareness. Never considered the possibility. Thanks for posting Glenn!

[Dean Egnater]

Scary stuff! The town grocery store burned when I was young for the same reason. How many rags were there?

Only 2....and not very big

[Dean Egnater]

I was Ipe deck oil.

[Dean Egnater]

They weren't in the can...the were on the can (to keep the finish off the BBQ) Though admittedly they weren't laid out

[Richard Coers]

The cord reel is really similar to running wire in conduit. You need a certain amount of open area in the conduit so heat doesn't build up. Cord reels can also have electrical contact issues. If you pull too many amps, the copper contact wipers can arc and burn out. Hopefully the sparks won't land in sawdust.
A salesman at the local tool and wood store had a total loss of his shop. He used danish oil finish and put the rags in a plastic garbage can. When he came out after supper, the whole shed was ablaze. The can started to burn, and since it was sitting next to his John Deere lawn tractor, the plastic gas can on it melted and caught fire also. From there the fire built at an incredible rate.

[Rick Potter]

One point to add.

The can you put rags in should be metal, not plastic.

Note OP's original pic.

[Austin Grote]

The electrical cord reels that I own have a warning label on them to always fully extend the cord when in use, they are at least 20 years old.

[Ken Combs]

The electrical cord reels that I own have a warning label on them to always fully extend the cord when in use, they are at least 20 years old.

JMHO, but that warning is only needed if you load the wire to its limit, or nearly so. Heat will not be generated in any appreciable amount when drawing 4-5 amps for a sander through a 14ga wire for instance. But if you have one of the cheap 16 gauge cord reels and use a 15a saw on it for a long time, it will heat.

Also, JMHO, but the vacuum makers that 'undercord' their vacuums should just put the right cord on it,nota warning label.

[Roger Feeley]

Has anyone deliberately tried to get rags to combust. I might want to demonstrate it sometime. I would like to set up something that would combust within an hour or two.

[Dan Friedrichs]

So what is the best practice with oily rags? I thought a closed metal can was correct, but according to the OP's picture, no?

[Wes Grass]

I thought I had a report saved on spontaneous combustion, but can't find it. Or online. It was based on mineral oils (which don't) but had some data on 'drying' vegetable oils as well.

They oiled rags or paper towels and wadded them up inside others for insulation with thermo-couples inside to measure temperature rise. Some had a measurable rise, some (mineral oils) had basically none. I think Linseed was already in combustion mode before their test period was over. For all practical purposes, it was the only one, from what I remember.

So it seems a fairly simple test. Paper towels would light up easier, I'd think. Probably need to experiment how much to soak them, and how much to wrap them up.

I heard a story about someone staining a fence and coming home and it had caught fire. Stories like this usually involve a neighbor kid who 'saw the fire start' and called the fire department. Which translates in my mind to: 'He smelled the solvent and wanted to see if it would burn".

Kid up by my place blamed it on some horseback riders throwing a molotov cocktail in the bushes. Firemen were like 'umm, yeah ... ok. If you see them again give us a call'.

[Pete Costa]

A year or so ago I was woken up at 1 in the morning by a very nice police officer who asked if that was my garbage can on fire out on the street. It was, in fact, my garbage can. I'd used BLO to finish a project a few weeks earlier and, knowing how dangerous those oily rags were, I spread them out over branches outside my shop to dry out. After what seemed like a very safe amount of time, I threw them in my garbage can, which then caught fire about six hours later. All I can figure is that it had been raining off and on while the rags were on the branches, so they must not have fully cured. Thankfully it was garbage day, otherwise the can would have been in my garage.

As for extension cords, I used to work at a fire protection engineering firm where we had a display wall of cords that had caught fire, sometimes with really bad results. The cheap ones with three sockets on the end seemed to be the worst. They are often overloaded and get scrunched up behind a sofa or something to get them out of sight. Don't do this!!!

[Jim Matthews]

So what is the best practice with oily rags? I thought a closed metal can was correct, but according to the OP's picture, no?

Submerged in water, if in a container.

Spread out to dry in a shaded patch of grass - away from structures you don't want burnt down.

[Rick Potter]

When I looked at the original pic, I assumed it was a plastic one gallon paint can. The metal lid was not damaged.

Let's ask the OP. Dean, was that paint can one of the newer plastic ones, or was it metal??